Traders have been left counting the cost after water poured in through the Market Hall roof – damaging thousands of pounds worth of goods and irreplaceable artefacts.

Freak weather hit the town centre causing water to seep through the roof of the Grade II listed building into balcony units and stalls below.

Precious pictures, books, clothing and historical artefacts loaned to the Hyndburn Heritage and Community Group (HHCG) museum were left ruined or badly damaged.

The Market Hall underwent a £2 million makeover just three years ago, with new stalls and balcony units installed and original stone flags brought back to their former glory.

One of the businesses worst hit in the deluge was Matthews Cards with water damaging expensive cake decorating equipment.

Owner Susan Holden said traders believed thousands of pounds worth of damage had been caused in the flooding. She added that staff only found out what had happened when they came in to work the next day.

She added: “It’s the second time this has happened in the last 12 months. The cake decorating section was all ruined.  We haven’t traded as normal since and our takings are down.  I realise that heavy rain is heavy rain but this stall has always been prone to it for many years despite the money they have spent on the roof.”

Three balcony units run by the museum group were damaged, with the school room ruined.

Alicia Ramell, members secretary of the group, said they were only just starting to recover from the damage caused over the weekend when more rain struck on Monday evening. She said: “The School Room was totally obliterated and everything was soaking wet. We were just paddling in it and every picture on the walk was wet. It’s just horrendous. It looked like somebody had just thrown water over everything in the room.

“It’s mainly photographs and books that people have lent to us and our records which show where the items have come from. In the Queen’s Room all the carpet was sodden but nothing was really damaged. Water seeped through the floorboards and landed on the Victorian apothecary shop and display units on the ground floor, however caused no permanent damage.

Bernard Scully, group vice chairman, said computers and paper records showing who had loaned the items to the group had been damaged. He said: “We don’t know yet exactly how much has been damaged. We have no insurance.”

Councillor Peter Britcliffe described the downpours as ‘torrential’ and called for a council investigation. He said: “It would test even the most rigorous of structures. It’s an old building and it’s important that the council investigates the problem and that it doesn’t happen again.”

The wet weather looks set to continue with more showers  forecast on Friday afternoon and Saturday, with the Met Office forecasting heavy showers in some areas after Sunday.

Cabinet Member for Markets and Deputy Leader Coun Clare Pritchard said: “It is very regrettable that Monday’s unprecedented flash flood caused problems in the market hall. 

“We are still assessing the damage but I am pleased that business is continuing as normal and I want to thank traders and staff for their efforts in clearing away the mess.  We are liaising with traders about damaged stock.  We are also investigating why so much rain came in to the building, with the intention of putting in place measures to ensure a similar flood does not happen again.”